Improvement in the manufacture of white lead



B. F. SMITH.

Manufacture of White Lead.

No. 22,679. Patented Jany 18, 1859.

U NITED STATES PATENT OFFICE.

IMPROVEMENT IN THE MANUFACTURE OF WHITE LEAD.

Hpeeiliealion forming part of [letters Patent No. 22,679., dated JanuaryI IRSJ.

lie it known that: I, lhcNJAMtN l SMITH, of New York, in the county andState of New York, have invented new and useful Improvements in theManufacture of \Vhite Lead; and I hereby declare the following to be afull, clear, and. exact description thereof, reterence being bad to theaccompanying drawing, which forms part of this specification, and whichrepresents a vertical section of an arrangement of apparatus forcarrying into ell'ect my invention.

My invention relates to the manufacture of white lead according to thedry process," in which metallic lead under the inllnenec of heat andmoisture is oxidized and combined with earl )Ullltj acid when exposed tothe action of acetic vapors or vapors from vinegar; and my inventionconsists in a peculiar disposition of the lead in the convertingchamber,insuring its elleclual exposure to the corroding notion of the saidvapors; and it further consists in the manner-of extraet ing from saidchamber the carbtmate formed therein pre viously to subjecting it to thewashing and drying processpvherelly the work men engaged in suchmannfaeture are proteeted against the injurious efl'eets attendant.thereon when conducted aoeortling to previous modes.

'lo distinguish my invention from precedin methods, I would state thatthe ordinary process as practiced in Holland, France, and Englandconsists in tirst placing, rolled lead sheets spirally arranged in lowpots containing vinegar and wine lees. .lhesc pots are put into chambersdug in the ground and surrounded with hot-settling, by which arrangementa temperature of about 50 centigrade is produced, the same beingnecessary to effect the corrosion of the metal in about six weeks. Thehorse-dung answers a double purpose namely, that of producing heat andthat of fnrnishingbyitsdecomposition carbonic acid. After this exposurethe lead sheets are taken out of the pots and unrolled,when thecarbonate formed from the lead crumbles in pieces, and is collected tobe broken between wooden rollers and afterward ground and mixed withwater, and the pastysubstanee thus produced placed in molds, where itremains three or four days, is dried, and sold in cakes. Besides theenormous expenditure of time, labor,

and apparatus incidental to such method of manufacture, said process ismost prejudicial to the health of the workmen engaged in earryine; itout, particularly that portion of it which relates to the detaching ofthe carbonate ol lead from the metallic sheets. 'lhese sheets arerequired to be shaken and tapped to detach adhering dust and powder thatform a considerable and valuable portion of the product. Such powder,being very light, forms a floating cloud, which the workmen necessarilybreathing they inhale a deadly poison. I am also aware that bytheAnstrian method of manufacture the lead sheets are hung over erossbars in ehambers. in the bottom of which vinegar-and wine leesareallowed to evaporate to ell'ect the corrosion of the sheets. Thesechambers are heated by horse dung, that supplies also the necessarycarbonic acid, or by steannpipes or hot-air ilues surrounding,- saidchambers. The sheets tints corroded are considm'ably incre: sed inthickness and contain a large quantity of. acetate of lead, which has tobe detached and the carbonate carefully and repeatedly washed. Both ofthese ln-iellyaleseribed processes are expensive and dan rermls to thehealth of the workmen. In the former n'oeessagreat quantity of metalliclead remains as a residuum ol' the manufacture, and this requires to beremelted, while in the latter process the production of acetate of leadis so great that it may be detached in perfect crystals hanging aboutand around the sheets.

My improvement, as will appear from the following (lOSttL'lPllOll,obviates the defects before mentioned as incidental to either of theprocesses just described.

'lhus I first prepare in any convenient manner the lead in smallspangles of (say) two inches in length, one-fourth of an inch width, andof the thickness of ordinary letter-paper (more or less) arched in theireross-section and ofarched or irregular form longitudinally, such aswould be formed by melted lead issu ing from a line oritice and fallingon a rap idly revolving" corrugated cylinder, cooling and breaking thestream and throwing the lead oil? in detached pieces. These spaugles Ipile or throw upon racks placed successively under said revolvingcylinder. The racks may be made of trellis-work and about;

lour hundred of them be used in each eon verting-rhainller, whichchamber may be about six leet high, twelve feet long, and six feet wide,and should he made with an inclined bottom, as shown in theaccompanyingdrawing. lh racks d l place in said chamber in double rowsbyarrangingthem first. in the rear and piling them up to or nearthe top,and gradually advancing to build up a row or rows of other racks infront of them. The chamber then containing the racks with spauglesonthem isearelully closed and lnled.

'lubes or pipes .r j/ are provided in the chamber at its bottom,establishinga communication between said chamber and a boiler or vinegartub li,thetnbesbeing closed when rctlllllCt'l by trap-valves r 1'. At ornear the top of the chamber is an opening I), closed by a trapwalvewhich is occasionally lifted to allow foul air to escape-that is, airwhich was in the tube and chamber previous to commencing work, andwhich, being lighter than carbonic acid, will rise and be expelled, saidopening also serving to increase the circulation when the chamber is toodensely filled and choking of the passages orobstruction is produced bymeans of a force-pu mp or seetion-blower applied thereto to effect aforced circulation.

I would state here that it may be advair tageous to combine themanufacture of white lead with thatof vinegar. The vapors rising fromthe fermenting-tub in the latter manufacture may thus be made availableand collected and forced into the convcrting-ehamher A, and by arrangingthe said chamber above or on a level higher than the outlet to the vaporfrom the fermenting-tub the natir rat ascent of the vapors will causethem to enter the chamber. Such combination ol manufacture, however, 1do not claim,as it is in common use abroad, and has been described inprinted publications of date long prior to this proposition of sucheconomy. Thcchamher A, 1 also provide with pipes or, entering at the topand serving to conduct the carbonicacid gas into the chambersimultaneously with the corrosion of the lead by the acetic vapors. Itwill be apparent that by this arrangement the most perfect circulationis produced, the carbonic acid gas descending, while the acetic vaporsascend among and through the several racks on which the spangles rest,and which, filling the chamber or thereabout, admit of no t-hrough-curren t in one direction more than another, but cause the gas andvapor to worn1"v their way in and among the spangles,and,as due to theirarched orirregular form and thinness, to act with perfect equality,certainty, and effect in converting the lead as required. Thedistribution of the lead span gles on the racks may be from one to twoinches in depth each successive series of racks or frames, which allowsof the fumes from below readily, but not too readily, passing throughthe mass to the top of the chamber, where the foul air may escape. Inall other llletlunls the lead is arranged with so much vacant spaceintel'vcningthat the fumes are at liberty to circulate where they tindthe largest. drafts, and the consequent result. is very unequaleorrositjm ol' the metallic lead. The lead in s 'iaugles thus acted onin a pen l'eet, regular, and equal manner, or there about, by the aceticl'nmes is soon converted into a sultacetatc olf lead, which in turn isdecomposed by the action of the carbonic-acid gas freeing the aceticacid that is again made available for further action on the metalliclead, and which process is being continually repeated. In from live toten days the lead spangles l )CCOlllt) by this treatment thoroughlycorroded, leaving in the chamber, instead of metallic lead, purecarbonate of lead intermixed, but only slightly, with acetate of lead,which is converted by an after process into carbonate of lead; or theproduct from the chamber maybe freed from the acetate of lead byrepeated washing.

The chamber being filled. with the converted product that is, carbonateof lcad-I proceed to extract it from. said chamber as follows: A pipe at(shown in the accompanying drawing) is made to convey from a boiler ortank steam or water into the chamber. \Vhen steam is used, I introducea. jet of it, the object of which is to saturate the carbonate of leadand so moisten it that the whole mass shall acquire a pasty consistencysomewhat like mortar, and the said jet further serves to expel the foulgases and air contained in the chamber, and wl1ich,being specificallyheavier, will be displaced and fall in the lower part of the chamber,from which they may escape by lifting a trapvalvc. In this way theworkmen are safely guarded against the obnoxious dust and vapors whichaccording to previous methods they have been forced to inhale whileremoving the lead from the chamber to the washingtub.

When the pipe d last referred to is used to convey water, I make orattach it as a hose, in order that it may be moved or worked from theoutside of the chamber in such a manner as to project its jet or streamin every direction within the chamber. In this case the washinglub isplaced immediately under the outlet of the chamber, and the carbonate oflead is washed out of the chamber without much delay or dilficulty andentirely by reason of the inclination given the bottom of the chamber,whereby all handling for transfer of obnoxious matter to the washingtubis avoided.

W hat I claim as my invention, and desire to secure by Letters Patent,is

l. The manner of filling the chamber with metallic lead by means of theopen-work tables or racks on which the lead in detached pieces rests,arranged one above the other in successive and close series,substantially as described, and whereby a more thorough and equalcirculation of the fumes or gases among the lead is produced.

L. ('oustrueting the eourertiug-vhzuuber other iueitlcutnl productsprevious to their with an inclined bottom,substantiallyas and extractionfrom the eonvertiug-vluuuher to for the purposes set forth the notion ofsteam, substmltinlly in the man I 'lhe method herein described ot'extra-tit uer and for the purposes specified. in; from theeonvertiugrhuuiber the wax-hon In testimon whereof I have siguml my autoof lead. mul other ineit'lentul products by name to this speeitimrtioubefore two sul means of a current or currents of water pausserihiug'witnesses. ing through said chamber from top to bottom, substantially inthe manner and for the oh- Witnesses: jeets herein set; forth. 1 A.POLLAK,

4. hubjeoting the enrhouztte of loud and i \VM. 1). RUSSELL.

